APPENDIX G: Marine Mammals Report ELD-247141-158-2445-V1 REPORT NO. 3316 MARINE MAMMAL ASSESSMENT FOR A PROPOSED SALMON FARM OFFSHORE OF THE MARLBOROUGH SOUNDS CAWTHRON INSTITUTE | REPORT NO. 3316 JULY 2019 MARINE MAMMAL ASSESSMENT FOR A PROPOSED SALMON FARM OFFSHORE OF THE MARLBOROUGH SOUNDS DEANNA CLEMENT, DEANNA ELVINES Prepared for the New Zealand King Salmon Co. Ltd CAWTHRON INSTITUTE 98 Halifax Street East, Nelson 7010 | Private Bag 2, Nelson 7042 | New Zealand Ph. +64 3 548 2319 | Fax. +64 3 546 9464 www.cawthron.org.nz REVIEWED BY: APPROVED FOR RELEASE BY: Simon Childerhouse Grant Hopkins ISSUE DATE: 1 July 2019 RECOMMENDED CITATION: Clement D, Elvines D 2019. Marine mammal assessment for a proposed salmon farm offshore of the Marlborough Sounds. Prepared for New Zealand King Salmon. Cawthron Report No. 3316. 38 p. plus appendices. © COPYRIGHT: This publication must not be reproduced or distributed, electronically or otherwise, in whole or in part without the written permission of the Copyright Holder, which is the party that commissioned the report. CAWTHRON INSTITUTE | REPORT NO. 3316 JULY 2019 EXECUTIVE SUMMARY The New Zealand King Salmon Company Limited (NZ King Salmon) want to develop a site for salmon farming in the deeper, high energy waters offshore of the Marlborough Sounds. The proposal area is located offshore of the Marlborough Sounds, due north of Cape Lambert, and east of the Chetwode Islands. The exact details of the number of pens and pen types are still to be confirmed. Cawthron Institute has been contracted to provide an assessment of the potential effects on marine mammals arising from the development of this proposed marine farm area. The greater Cook Strait and South Taranaki Bight region, in association with Marlborough Sounds waters, is considered an important area for a large number of New Zealand’s cetacean and pinniped species as well as a vital migration corridor for several whale species. The species that occur in the vicinity of the proposal are common, bottlenose and dusky dolphins, NZ fur seals, orca, southern right and humpback whales. While the proposed farm area represents a very small fraction of the total habitat available to support these marine mammal species, it potentially constitutes important winter habitat for southern right whales and forms part of humpback whales’ northern migration corridor. Marlborough Sound waters also support sub-populations of nationally threatened bottlenose dolphins, Hector’s dolphin and orca, which need to be considered. Impacts on marine mammals from aquaculture result from an overlap between the activity and the habitat use and / or migration routes of the species. The main effects of the current proposal are possible habitat displacement or avoidance and entanglement risk. Other impacts considered include underwater noise, artificial submerged lighting and trophic flow- on effects. While the overall likelihood of any adverse effects is considered low, the consequences of a rare event such as the fatal entanglement of threatened species warrants appropriate mitigation actions. To ensure that the most appropriate measures are in place, an update of the current Marine Mammal Management Plan (MMMP) prior to commencing operations is recommended along with several suggested best management practices regarding the set-up and operation of open ocean marine farms that can help further reduce the risks of entanglement and other adverse effects. It is acknowledged that there are still knowledge gaps and uncertainty around how marine mammals will perceive open ocean farm structures visually and acoustically, and importantly, the results of their reactions to farms. Recommended mitigation actions are aimed at addressing some of these gaps, including documenting how marine mammals respond to the proposed farms, while assessing the effectiveness of any mitigation measures put in place. i CAWTHRON INSTITUTE | REPORT NO. 3316 JULY 2019 TABLE OF CONTENTS 1. SCOPE OF WORK ........................................................................................................ 1 1.1. Description of proposal ................................................................................................................................... 1 1.2. Scope of assessment ..................................................................................................................................... 2 2. DESCRIPTION OF EXISTING ENVIRONMENT ............................................................ 3 2.1. Species of concern ......................................................................................................................................... 9 2.1.1. Species summary .................................................................................................................................... 12 3. ASSESSMENT OF EFFECTS.......................................................................................14 3.1. Habitat exclusion or displacement ................................................................................................................ 14 3.1.1. Baleen whales ......................................................................................................................................... 15 3.1.2. Odontocetes and pinnipeds ..................................................................................................................... 16 3.2. Entanglement ............................................................................................................................................... 18 3.2.1. Baleen whales ......................................................................................................................................... 19 3.2.2. Odontocetes and pinnipeds ..................................................................................................................... 19 3.3. Underwater noise disturbance ...................................................................................................................... 23 3.4. Artificial lighting ............................................................................................................................................. 24 3.5. Possible flow-on effects due to alterations in trophic pathways .................................................................... 24 3.6. Cumulative impacts ...................................................................................................................................... 25 4. MITIGATION .................................................................................................................27 5. CONCLUSIONS ............................................................................................................30 6. REFERENCES .............................................................................................................32 7. APPENDICES ...............................................................................................................39 iii JULY 2019 REPORT NO. 3316 | CAWTHRON INSTITUTE LIST OF FIGURES Figure 1. Proposed location of the open ocean farm development ................................................... 1 Figure 2. An example schematic drawing of a ‘Fortress’ pens by Huon aquaculture, similar to those that may be considered in this proposal. .................................................................. 2 Figure 3. The spatial locations of systemic and opportunistic marine mammal sightings (whales, dolphins and pinnipeds) and strandings reported within the general Cook Strait region and associated waters of both the North and South Island, including the South Taranaki Bight and Marlborough Sounds. .......................................................................... 4 Figure 4. The distribution of Department of Conservation (DOC) reported strandings (1912– 2015) and opportunistic sightings (1977–2018) within the greater Cook Strait region. ...... 8 Figure 5. Marine mammal interactions with marine finfish aquaculture sites in British Columbia listed by species and year ................................................................................................. 21 LIST OF TABLES Table 1. Summary of potential effects on marine mammal species from the proposal. ................. 26 Table 2. Proposed best management goals and practices (BMP) to minimise the risk of any adverse effects of the proposed farms on marine mammals in Cook Strait waters. ........ 29 LIST OF APPENDICES Appendix 1. Data sources for this assessment. .................................................................................... 39 Appendix 2. Records of known marine mammal entanglements in marine farms within New Zealand. ............................................................................................................................ 40 Appendix 3. An example of marine mammal sightings collected from Australian experimental finfish farm off New South Wales (NSW 2018; https://www.huonaqua.com.au/wildlife- interactions/). ..................................................................................................................... 41 iv CAWTHRON INSTITUTE | REPORT NO. 3316 JULY 2019 1. SCOPE OF WORK 1.1. Description of proposal NZ King Salmon want to install salmon farms in open ocean areas due to improved environmental conditions for farming and reduced biosecurity risk. The proposal area is 1,800 ha, northeast of the Marlborough Sounds, due north of Cape Lambert, and east of the Chetwode Islands (Figure